1. Field of the Invention
The present invention is in the field of telecommunications. In particular, the present invention relates to the routing of modem calls to internet access providers by the telephone system. Specifically, the present invention involves digital loop carriers which interface individual telephone lines to telephone central offices.
2. Discussion of the Related Art
The increasing demand for internet access is resulting in a corresponding increase in the utilization of public local telephone system resources. A telephone subscriber typically accesses the internet through an internet access provider. The telephone subscriber has a calling modem attached to his computer, and the calling modem places a call to the internet access provider""s receiving modem through the public local telephone system, which also carries voice, facsimile, and other data transmissions. The connection from the calling modem""s line to the internet access provider""s receiving modem is typically accomplished via a free local telephone call that often has a statistically lengthy duration in comparison to a typical voice call.
In telephone networks, several telephone lines each having a unique telephone number are first routed to a digital loop carrier, rather than directly to the local central end office. The digital loop carrier has communication trunks to the local central end office, which provide a time multiplexed communication channels to the local central end office. The trunks between the digital loop carrier and the local central end office carry a limited number of DS0 communication channels. Each DS0 communication channel provides enough communication bandwidth to carry a single call. Because the telephone company realizes that many telephone numbers will likely be idle at any given time, there are fewer DS0s available in the trunks from the digital loop carrier to the local central end office than there are telephone numbers being served by the digital loop carrier. When a call is initiated, a DS0 is allocated to the call; at the end of the call, the allocated DS0 is freed up so that it may then be allocated to another new call.
Conventionally, when a calling modem initiates an internet session by dialing an internet access provider, a DS0 in a digital trunk from the digital loop carrier to the local central end office is allocated to the call, and the call is routed through the local central end office for the duration of the internet session. This allocation of the DS0 and allocation of the local central end office switch resources occupies the capacity of the local central end office for the duration of the internet session, thereby limiting the ability of the local central end office to service other calls. The congestion caused by internet calls degrades the performance of the public local telephone systems. As is apparent from the foregoing discussion, it would be desirable for the telephone company to free up as much of the existing public local telephone system""s resources as possible while still providing internet access.
Conventional telephone network systems which route modem calls that are directed to a local internet access provider and which originate from a telephone number serviced by a digital loop carrier require the allocation of resources in the digital loop carrier, the trunks connecting the digital loop carrier to the local central end office, and the local central end office. Using conventional telephone network systems, these allocated resources are fully occupied during the often lengthy duration of the user""s internet session. Numerous internet access calls can congest the conventional telephone switching system to the point where it is unable to service new calls. A need exists for freeing up valuable telephone network resources during an internet call while still providing the ability to connect a calling modem""s line to an internet access modem bank.
According to the present invention, the time slot interchange capabilities of modern digital loop carriers are utilized to provide more direct connectivity from the calling modem""s line to an internet access modem bank through the digital loop carrier, thereby bypassing the local central end office. A call which is to a telephone number of an internet access provider""s modem is routed to a bypass initiator. If the bypass initiator detects that the call is from a number which is serviced by a digital loop carrier having a local central end office bypass capability, then the bypass initiator will issue a bypass command. According to the present invention, the digital loop carrier establishes the bypass connection, but does not break the signaling connection on the initial call which was routed from the digital loop carrier through the local central end office to the bypass initiator. Once the bypass connection has been established, the bypass initiator sends a disconnect signal through the signaling connection of the initial call. Because the signaling from the calling modem""s line still indicates an off hook status to the local central end office due to the bypass connection, the local central end office begins permanent signal treatment procedures. The permanent signal treatment procedure results in the calling modem""s line being placed in the permanent signal state at the local central end office, so that the telephone system will know that the calling modem""s line is unavailable for incoming calls. When the bypass connection is complete at the end of the internet session, the calling modem""s line goes on hook and is reported to the local central end office in the conventional manner.
In an embodiment of the present invention, the bypass initiator exists at the internet access provider""s receiving telephone modem. The bypass initiator has the capability to receive the caller""s telephone number using Caller ID or Automatic Number Identification procedures. The telephone company periodically updates the internet access providers"" databases with the list of telephone numbers which are serviced by digital loop carriers capable of bypassing the local central end office.
In other embodiments of the present invention, each telephone line corresponds to a specific bypass initiator which is maintained in the telephone system. In these embodiments, the bypass initiator logically includes two tables, one table including the list of called telephone numbers which have modems connected to the internet, and the other table including the list of calling telephone numbers which are serviced by digital loop carriers having local central end office bypass capabilities. According to an embodiment, each local central end office includes a bypass initiator. In this embodiment, the calling number table only includes the calling numbers which are serviced by digital loop carriers having local central end office bypass capabilities that are serviced by that particular local central end office. According to another embodiment, there is a centralized bypass initiator for the telephone system which refers to a centralized table. Both the calling number table and the called number table include telephone numbers serviced by more than one local central end office.
These and other features and advantages of the present invention are described in the Detailed Description of the Invention in conjunction with the Figures.